This invention relates generally to containers. In particular, the present invention is directed to a triple-action latch for securing together the housing members of a magnetic tape cassette shipping case.
Latch assemblies for containers are in wide spread use. A typical latch for a blow-molded plastic box is disclosed in the Weavers U.S. Pat. No. 4,153,178. The plastic box includes a cover part hinged to a container part. The latch assembly includes a flexible slide that fits around the shoulders of a T-shaped rail which is integral with a side wall of the cover part. The slide is movable along the T-shaped rail between open and locked positions. One shoulder of the rail and a portion of the slide are formed with notches which are aligned when the slide is in the open position. A tab integral with a side wall of the container part fits into the notch in the T-shaped rail when the plastic box is closed and the slide is at the open position. The tab is retained within the notch by a side edge of the slide upon movement of the slide towards the locked position and thereby acts to latch the cover part and container part together. A detent integral with the slide is configured for snap-fitting engagement with an end portion of the T-shaped rail when the slide is at its locked position to provide a second latching action.
However, this double latching action is not always effective to latch the cover part and container part of such a plastic box together. In actual use, the detent has sometimes been accidentally dislodged from its snap fit engagement with the end portion of the T-shaped rail and further jarring has allowed the slide to move to the open position, thus unlocking the plastic box so that its contents could spill out. Moreover, the plastic box when produced must be shipped to production plants with the slide in its locked position (so that the detent is at rest) to allow the plastic detent to cold flow or take a set during shipment. This procedure required production plants to unlock the box (by disengaging the detent from the T-shaped rail and then moving the slide to the open position) before a magnetic tape cassette could be inserted into the box for shipment to customers.
It is evident that there is a continuing need for improved latch assemblies for containers. Specifically, there is a need for a latch assembly that includes a movable slide having a pair of detents that lock the slide against movement to better insure that the slide is not accidentally jarred to its open position, thereby unlocking the container and spilling its contents. In addition, there is needed a latch assembly with a plastic slide that can be left in the open position to allow its plastic detents to cold flow or take set during shipment to production plants. This procedure saves time and money at production plants since the container no longer must be unlocked to permit goods to be inserted into the container for shipment.